1. Technical Field
The present invention relates to a liquid ejecting apparatus that has a function of liquid agitation utilizing the boiling of liquid at reduced pressure.
2. Related Art
Some printing apparatuses, which is an example of various types of liquid ejecting apparatuses, use ink that contains a color component that is insoluble or hardly soluble in a solvent. For example, in pigment-based ink, fine particles of pigment are dispersed as a color component in a solvent such as water, a petroleum solvent, or the like. Accordingly, the pigment is apt to precipitate. For example, the specific gravity of white pigment is approximately four. The specific gravity of metallic pigment is approximately two to three. In contrast, the specific gravity of a solvent is less than one. Since a difference between the specific gravity of the pigment and the specific gravity of the solvent is greater than one, the pigment is apt to separate from the solvent and thus precipitate.
In addition, dye is apt to precipitate in some dye ink that contains insoluble dye or hardly soluble dye as a color component. When the color component of ink precipitates, light and dark color-density irregularities occur in the ink. Therefore, in such a case, it is impossible or difficult to supply ink having uniform concentration to a head. A portion of the ink that has greater density might clog the nozzles, which results in a difficulty in discharging ink drops from the nozzles. As another problem, the luminance of dots might deviate.
In an effort to provide a solution to these problems, a technique for agitating (i.e., stirring) ink by means of a plurality of float-and-sink bodies that are present in ink contained in an ink-containing chamber has been proposed as disclosed in JP-A-2005-28686. Specifically, according to the related art disclosed in JP-A-2005-28686, the ink-containing chamber contains the float-and-sink bodies, which change in volume in accordance with a change in the pressure of ink, together with the ink. A pressurizing pump changes the inner pressure of the ink-containing chamber so that the float-and-sink bodies float and sink in the ink. The ink is agitated through the movement of the float-and-sink bodies.
In the related art disclosed in JP-A-2005-28686, the ink-containing chamber is supposed to contain more than one float-and-sink body. Therefore, the ink capacity of the ink-containing chamber decreases by the aggregate volume of the float-and-sink bodies. As another disadvantage, there is a risk that the float-and-sink bodies will block an ink drain port, which is less reliable. As another disadvantage, the float-and-sink bodies might not diffuse well to reach the inner corners of the ink-containing chamber. Therefore, there is a possibility that ink cannot be agitated at the corners completely.